Compositing fire into footage with Davinci Resolve
Why did you give up on using EXR (I have tried to import EXR files to Davinci Resolve with the LUT&#39;s) and go to a useless format like PNG?
PNG cannot handle associated alpha channel, it cannot have pixels that are emissive and transparent at the same time.

Go back to EXRs and be happy.

As for the glow on other elements you have two choices: Create some geometry in blender that will be affected by the fire and use it to add luminance to the scene in the compositor of your choice (fusion can do that) or even as a video track over the original footage in davinci. Or use masks on the footage and selective color correction and try to recreate the effect on other elements of the scene. 

In the world of movie-making, such scenes are shot with the special effect in mind, usually having lights that flicker and simulate the color and brightness of the fire. You will find out that it is hard to replicate after the fact. The intensity, direction and movement of the shadows to make a convincing effect will require a lot of work if it was not done in the original plate.